New nitriding process of high-alloyed maraging steel for cryogenic operation

Abstract

The paper considers the gas nitriding process with cyclic alternation of atmospheres: ammonia and an ammonia mixture with air for strengthening the corrosion-resistant high-alloyed steel 03Cr11Ni10Mo2Ti, designed to operate at cryogenic temperatures. The formation in steel of a nitrided layer of 130—150μm thickness with increased microhardness (more than 12GPa) is shown experimentally. During the final stage in the ammonia and air environment, iron oxides remain in the compound zone, and a sharp drop in hardness is observed at the border of the core. At the completion of the cyclic process with the stage of saturation in ammonia, a nitrides zone is formed based on the γ′-phase, the layer thickness increases (up to 180(…200μm) and the microhardness profile is smoothed, which reduces the risk of embrittlement.

The effect of stadial nitrogenization on the structure and properties of martensitic steel 13X11N2V2MF

“…Интенсификация азотирования достигается также применением многокомпонентных атмосфер, в том числе, путем термо-и газоциклирования [9 -11]. Так, циклические процессы с чередующейся подачей аммиака и воздуха не уступают процессам ионно-плазменного азотирования по скорости формирования азотированного слоя, создают дополнительные возможности регулирования фазового состава слоя и получения заданных свойств как в углеродистых, так и в легированных сталях [12,13].…”

Surface Strengthening of High-Alloyed Martensitic Steel by Staged Nitriding

“…Another way for nitriding acceleration consists in application of staged or cyclic processes with changing of nitriding potential. It was shown that cyclic processes in changing ammonia-air atmospheres provide specific opportunities for phase composition regulation and for achievement of given properties of nitrided surface [5,6].…”